Roller hearth tunnel kilns



July 4, 1967 P. DH. DRESSLER ROLLER HEARTH TUNNEL KILNS 2 Sheets-Sheet l Filed June 24, 1965 Philip dETIYEETrgsRsIer July 4, 1967 P. D'H. DREssLER 3,328,861

ROLLER HEARTH TUNNEL KILNS INVENroR Philip d'H. Dressler United States Patent O M 3,328,861 ROLLER HEARTH TUNNEL KILNS Philip dH. Dressler, Pittsburgh, Pa., assigner to Pullman Incorporated, Pittsburgh, Pa., a corporation of Delaware Filed June 24, 1965, Ser. No. 466,646 9 Claims. (Cl. 25--142) This invention relates to heating kilns and the like and is particularly directed to the construction of kilns having roller conveyors therein.

The manufacture of ceramic tile -and other ceramic ware is notoriously old. Indeed, ceramic ware is one of the oldest manufactures known. Ceramic ware was, of course, made and tired by hand in batches during prehistoric times and even later. As technology developed, it became common to provide continuous kilns in which the uniired ware is supplied at one end of the kiln and is moved slowly through it during which time it is heated to tiring temperatures and then cooled as necessary to avoid cracking and breakage due to thermal shocks caused by excessive temperature differentials.

Some types ceramic ware in common use today have been known and used for hundreds if not thousands of years. For example, ceramic tile, substantially identical to tiles which are manufactured today, is found in buildings dating back into ancient times. That is, they have a thickness of about and are from about 4%" to 6" square.

In moving ceramic ware through a continuous kiln a serious problem has always existed in providing some form of conveyor that will withstand the heat required for efficient firing. Various forms of conveyors have been suggested or used including metallic belts, movable plates, and roller conveyors. All such devices have substantial shortcomings. When moving conveyors are employed, for example, the mass of the conveyor must be heated as it advances through the kiln. Metals which are alternately heated and cooled exhibit the undesirable characteristic of scaling and thereby contaminating ceramic ware. In some cases, the amount of heat required to heat a moving conveyor mechanism greatly exceeds that required to iire the ware.

It has also been proposed to employ roller conveyors. Such rollers are subject to the objection that the rollers cannot readily be removed land installed and are necessarily connected into the drive train in such a manner as to make a semi-permanent connection. A further problem is that roller conveyors of the types proposed have generally required large rolls which are unable to transport small pieces of ceramic ware, and the use of pallets would be required. Such would require additional handling of the ware to load the pallet and also add to the amount of material which must be unnecessarily heated. A further problem is that one or more rolls within the kiln may break or become damaged. It is desirable to replace those rolls without completely tearing down the kiln and preferably without interrupting production through it. Prior designs have required an elaborate tearing down of the kiln and shutting down of the drive mechanism for that purpose. Such may result in uneven firing of ware within the kiln or the influx of substantial quantities of cold air upsetting the heat balance of the kiln. A further problem which arises is that wrecks may be expected to occur from time to time, even within the best regulated kilns. It is necessary in such circumstances that the wrecked ware be cleared away promptly to enable a continuous stream of ware to pass through the kiln. Where a piece has lodged between two rolls dismantling or fishing may be required to remove it, thereby impeding production and disrupting the operation of the kiln.

I have invented new and useful improvements in kiln 3,328,861 Patented July 4, 1967 ICC design which overcome the foregoing problems and permit ware of small size to be passed through a kiln without the necessity of pallets, setters, and the like. I provide a kiln having heated chamber, apertures in the side walls of said chamber and a plurality of conveyor rolls extending through said apertures and through the kiln with the ends of the conveyor rolls being external to the heated chamber. Externally of the kiln I provide a plurality of rollers journaled for rotation and having their circumfercnces generally tangential to the ceramic rolls projecting from the heated chamber. I prefer to set the conveyor rolls upon and between the external rollers whereby the conveyor rolls rest between and are supported by two adjacent external rollers. I further preferably provide power means in operative connection to the external rollers whereby said external rollers are driven rotatably. I may form the conveyor rolls of ceramic material and preferably employ ceramic conveyor rolls in at least the hottest portions of the kiln.

I further prefer to provide stop means adjacent the ends of the conveyor rolls, limiting and controlling axial movement of the conveyor rolls. I may provide means to press the conveyor rolls downwardly onto the external roller for better Contact therebetween. I further prefer to make at least one of the stop means readily removable. In this manner the stop means may be promptly removed and the conveyor rolls withdrawn yaxially from the heated chamber.

Other details, objects, and advantages of my invention will become more apparent as the following description of the preferred embodiments are presented.

In the accompanying drawings I have illustrated a preferred embodiment of my invention in which FIGURE 1 is a partial longitudinal vertical cross section through a kiln embodying my invention;

FIGURE 2 is a vertical transverse cross-sectional view through the kiln shown in FIGURE l;

FIGURE 3 is an enlarged fragmentary cross-sectional view of the roller hearth of the kiln shown in FIGURE l;

FIGURE 4 is a fragmentary side elevational view of the roller hearth of the kiln shown in FIGURE 3 partly in section and viewed from the left; and

FIGURE 5 is `a fragmentary side elevational view of the roller hearth of the kiln of FIGURE 3 partly in section and viewed from the right.

Referring to FIGUR-ES l and 2 a kiln 10 has an outer bottom wall 12, a ceramic lining 14 and a heated chamber 22. The side walls 34 and 36 have burner tiles 16. Battles 18 and 26 Vare suspended from the roof 20 to prevent heat from escaping at the entry 28 and exit 30 of the heated chamber 22. Apertu-res 24 are formed in both side walls 34 and 36 of the heated chamber 22. Each of the apertures 24 `are aligned with a corresponding aperture 24 in an opposite wall of the heated chamber 22. The apertures 24 are spaced apart and form a line along each wall 34 and 36 of the heated chamber 22. Rolls 32 are fitted through opposed apertures 24 and are preferably of ceramic material. It may be desirable in some circumstances, however, to employ metallic rolls in at least the low temperature sections of the kiln. Ceramic ware which is to be tired in the kiln enters at 28, progresses through the kiln upon rolls 32, and exits at 30. The ceramic roll members 32 extend outwardly from Walls 34 and 36 at 38 and 40 respectively.

The structure moves a ceramic piece from the entry 28 to the exit 30 along the conveyor comprising ceramic rolls 32 spaced apart in planar succession. The ceramic rolls 32 are preferably positioned relatively close together so that the ceramic ware can be carried without falling between the rolls 32. This eliminates the need for a pallet to carry the ware thereby improving the heat control of the ceramic ware. When firing ceramic ware of approximately four inches in length, ceramic rolls 32 having a 1%. outside diameter and placed no more than two inches apart will handle the Ware in s-atisfactory fashion.

The use of such small diameter conveyor rolls 32 poses a drive problem. A direct drive to a motor means is diiiicult because of the coupling problems and the necessity of replacing rolls or temporarily removing them to allow wrecked ware to fall to the bottom of the kiln.

Referring to FIGURES 3, 4 and 5, ceramic conveyor rolls 32 span across the heated chamber 22 of the kiln 10. The ceramic rolls 32 extend outwardly from walls 34 and 36 at 33 and 4t) respectively. Exterior roller members 42 are positioned slightly beneath ceramic rolls 32 parallel to and spaced from the wall 34. Each ceramic roll member 32 rests within the cusps formed by and upon the surfaces of two exterior roller members 42. The engaging surfaces between the exterior rollers 42 and the ceramic roll 32 are tangential to each other. The shaft 44 of exterior roller members 42 passes through exterior roll housing 46 within which the shaft 44 is journaled for rotation. At the 'outside end of the shaft 44, a sprocket 48 is mounted which engages endless chain 50. The endless chain 50 is driven by chain reduction through sprockets 51, 68, and 70 and chain 72 all driven by motor 52. The other end of each ceramic conveyor roll 32 rests on a pair of idler rollers 54. To prevent axial movement, retainers 56 and 58 are placed along and adjacent to the ends of the rol-ler projections 38 and 40u The ends of the .rolls 32 terminate in bearing surfaces or caps 60 and 62 having a spherical surface. If each roller 32 comprises a hollow ceramic tube, a unit may conveniently be inserted in each end to serve as a bearing surface. Should a ceramic roller 32 shift axially, one of caps 60 and 62 will strike and rub against roll bar retainers 56 or 58 limiting further axial movement.

In order to replace a broken ceramic roll member 32 or to drop a Wreck which is resting on a particular group of rolls 32 the appropriate retainers 56 or 58 is removed and the broken roll or the roll upon which the wreck is sitting can be removed and replaced. Such an arrangement ydoes not require stoppage of the drive system driving the rest ofthe rolls along the length of the kiln.

In the event that the ceramic ware to be red is not heavy enough to press down the ceramic roll 32 into engagement with a pair of exterior roll members 42, an idler roll 64 spring-biased by spring 66 toward the ceramic roll member 32 may be provided to supply suflicient pressure for frictional engagement between ceramic roll 32 and exterior roll member 42. This arrangement is shown in chain lines.

While I have set out certain preferred practices and embodiments of my invention in the foregoing specification, it will be understood that I do not limit myself thereto and that the invention may be otherwise practiced within the scope of the following claims.

I claim:

1. A kiln comprising:

(l) A heated chamber having a plurality of apertures in the walls of the chamber;

(2) A plurality of conveyor roll members consisting essentially of ceramic material projecting through the walls of the chamber, and spanning across the heated chamber; and

(3) A plurality of roller members positioned exteriorly of the heated chamber and positioned to receive and cradle between two of said roller members a portion of one of the ceramic conveyor roll members.

2. A kiln comprising:

(1) A heated chamber having a plurality of apertures in the walls of the chamber;

(2) A plurality of ceramic conveyor roll members formed from ceramic material only projecting through the walls of the chamber, 'and spanning across the heated chamber;

(3) A plurality of roller members positioned exteriorly of the heated chamber and positioned to receive and cradle between two of the lroller members a portion of each of the ceramic conveyor rolls; and

(4) Means rotating the external roller members whereby the ceramic conveyor rolls are frictionally rotated by the external roller members.

3. A kiln comprising:

(l) A tiring chamber having a plurality of opposed apertures in opposite walls of the chamber;

(2) A plurality of spaced .apart ceramic conveyor roll members consisting essentially of a ceramic material of substantially uniform diameter projectingthrough the apertures in the walls of the tiring chamber and extending outwardlly from the Walls;

(3) A plurality of exterior roller members positioned exteriorly of the firing chamber, the circumferential surfaces of at least two of the exterior roller members being tangent to one of the ceramic conveyor roll members projecting through a pair of opposite apertures, whereby opposite ends of the ceramic conveyor roll members rest between and are carried by a pair of exterior roller members; and

(4) Means rotating the exterior roller members whereby the ceramic conveyor rolls are frictionally rotated by the exterior roller members.

4. A kiln comprising:

(l) A heated chamber having a plural-ity of apertures in opposite walls of the chamber, the apertures on each wall being spaced apart and in corresponding alignment with the apertures of the opposite wall, the centers of adjacent apertures forming a line along the wall of the chamber wall;

(2) A plurality of conveyor roll members, each spanning across the heated chamber and projecting through the oppositely aligned apertures and extending out from each wall of the chamber;

(3) A plurality of exterior roller members journaled `for rotation and positioned exteriorly of the heated chamber and of one apertured wall of the chamber, the exterior roller members positioned to receive and cradle tangentially between two exterior roller members one end of a conveyor lroll member whereby one end of each conveyor roll member rests between and is carried by a pair of exterior roller members;

(4) Means rotatably supporting each end of the conveyor roll members opposite the end engaging the exterior roller members;

(5) Means rotating the exterior roller members Where- -by the conveyor rolls are frictionally rotated by the exterior roller members; and

(6) Means adjacent the ends of the conveyor rolls, limiting and controlling axial movement of the conveyor rolls, said means being removable to facili-tate replacement of the conveyor rolls.

5'. A kiln comprising:

(l) A heated chamber having a plurality of apertures in opposite walls of the chamber, the apertures on each wall being spaced apart and in alignment with the apertures in the opposite wall, the centers of adjacent apertures forming a line along the wall of the chamber; Y

(2) A plurality of conveyor roll member each spanning across the heated chamber and projecting through the oppositely aligned apertures and extending out from each Wall of the chamber;

(3) A plurality of exterior roller members journaled for rotation and positioned exteriorly of the heated chamber and of one apertured wall of the chamber, the exterior roller members positioned to receive and cradle tangentially between two exterior roller members one end of a conveyor roll member whereby one end of each conveyor roll member rests between and is carried by a pair of exterior roller members;

(4) Means rotatably supporting the end of the conveyor roll members opposite the ends engaging the exterior roller members;

(5) Means rotating the exterior roller members whereby the conveyor rolls are frictionally rotated by the exterior roller members;

(6) Means adjacent the ends of the conveyor rolls,

limiting and controlling axial movement of the conveyor rolls, said means being removable to enable replacement of the ceramic rolls; and

(7) Means pressing the conveyor rolls downwardly on to the exterior roll members for better frictional contact.

6. A kiln as recited in claim 5 wherein the means rotating the exterior roller members comprises, .a sprocket mounted on the end furthest from the chamber wall of each exterior roller Imember, an endless chain engaging all of the sprockets and means driving the endless chain.

7. A kiln as recited in claim 6 wherein the means aidjacent the ends of the conveyor rolls limiting and controlling axial movement comprises, a bar retainer adja-v cent the ends of the conveyor roll members projecting from the chamber walls, the bar retainer being spaced from the chamber wall to allow limited axial movement,

and being removable to allow replacement of the ceramic roll.

8. A kiln as recited in claim 7 wherein the means pressing the conveyor rolls downwardly comprises a plurality of idler rolls resting on top of the conveyor rolls and a spring biasing each idler rolls downwardly.

9. A kiln as recited in claim 8 wherein the means rotatably supporting each end of the conveyor roll members comprises a plurality of supporting roller mem-bers journaled for rotation, the end portion of each conveyor roll member resting between a pair of supporting roller members.

References Cited UNITED STATES PATENTS 896,172 -8/1908 Thomas. 1,938,581 12/1933 Cope et al 25-142 1,989,957 2/ 1935 Walters. 2,519,250 8/1950 Jeppson et al 25-142 X 2,577,935 12/1951 Van Der Pyl 25-142 2,945,279 7/ 1960 Bossetti 25-142 WILLIAM l. STEPHENSON, Primary Examiner. 

1. A KILN COMPRISING: (1) A HEATED CHAMBER HAVING A PLURALITY OF APERTURES IN THE WALLS OF THE CHAMBER; (2) A PLURALITY OF CONVEYOR ROLL MEMBERS CONSISTING ESSENTIALLY OF CERAMIC MATERIAL PROJECTING THROUGH THE WALLS OF THE CHAMBER, AND SPANNING ACROSS THE HEATED CHAMBER; AND (3) A PLURALITY OF ROLLER MEMBERS POSITIONED EXTERIORLY OF THE HEATED CHAMBER AND POSITIONED TO RECEIVE AND CRADLE BETWEEN TWO OF SAID ROLLER MEMBERS A PORTION OF ONE OF THE CERAMIC CONVEYOR ROLL MEMBERS. 